Process for refining hydrocarbons



' April 19, 1938. w. p ficK JR 2,114,313

PROCESS FOR REFINING HYDROCARB'ONS' "ori inal Filed March 16, 1935Patented Apr. 19', 1938 UNITED STATES PATENT PROCESS FOR. REFINING mzmocsanoss Walter A. Patrick, Jr.,

Application March 16,

Renewed February 8, 1938 4 Claims. The present invention is an improvedchemical treatment of mineral oils and distillates and the productthereof. In its primary application, the invention relates to thechemical treatment and purification of petroleum hydrocarbons, such ascrudes, distillates, products 'from' cracking, as well as oils derivedfrom the processing of shales and coke oven products such as light oilsand distillates thereof. I

The invention will be described inconnection with the treatment ofpetroleum hydrocarbons but it is to be understood that the process isequally applicable upon shales and coke oven products. In spite of mucheffort and study, the method sired refining of nearly all petroleumproducts, is that suggested .in 1855 by Silliman-treatment withconcentrated sulphuric acid followed by washing with sodium hydroxidesolution. The objections to the sulphuric acid wash are generallyrecognized, but no suitable refining substitute has yet been madeavailable (Petroleum and its Products Gruse-1928, page 121).

The present invention has as an object to provide an improved refiningprocess and a superior product without recourse to the conventionalsulphuric acid treatment.

An object of the invention is to obtain in:

troleum products, for example, gasoline, lubricating oils and kerosene,by a method afiording a product substantially free from deleterious.

substances, s'uch' as those which are easily .oxidizable or otherwiseunstable as well as resinous and asphaltic materials and sulphurimpuritiesv or compounds. The presenceof such substances in theoils ordistillates is generally recognized as impairing the quality of the,product.

- Another object 01' the invention is to manu- 40 iacture gasoline, ofhigh quality without recourse to blending. 'I'hat is to say, thenaphthas treated in accordance with the present invention do not havetheir valuable saturated and unsaturated hydrocarbons substantiallyafi'ected, and the final product has an octane number considerablyhigher than that obtained by conventional operations.

The invention comprises treating the mineral oils and distillates, oilsderived fromvthe processing of shale and coke oven products such as.

light oils and distillates thereof with a sulphur halide or reagentswhich react to form a sulphur halide. y

Kendall in his Patent No. 413,187, October 22, .1889, suggests the useof sulphur chloride to 56 deodorize certain oils preliminary to the use0! almost universally used to bring about the de-- the sulphuric acidtreatment and the deodorizing effector sulphur chlorides has, therefore,been recognized. Meigs (Industrial 8: Engineering- Chemistry, July 1917,page 655) discusses the .use of sulphur chloride and carbon disulphide 5solution in large amounts for testing asphaltic materials and gas engineoils for bituminous content. Lorand (Industrial & Engineering Chemistry,June 1927, page 733) discusses the laboratory use of sulphur chloride inlarge amounts as a testing material for petroleum hydrocarbons withoutrelation to the re ning of the same. Jaeger in his Patent No. 1:74 05,December 31, 1929 discusses the chlorination of aliphatics and thiopenecompounds contained in coal tar and its. derivatives using sulphurchloride as a carrier.

' Many halides of metals and metaloids have been sugg sted as refiningreagents of petroleum products notably AlCla, ZnClz, and FeCla, andothers such as AsCla, SbCla, SnCh have also 20 been mentioned; Their usewas directed either to cracking or to cause the complete removal ofunsaturated aliphatic hydrocarbons. The halides of sulphur are milderpolymerizing agents than the metallic chlorides, making it possible toselect conditions that will result in only the elimination ofobjectionable. constituents of the oil. 1

I have discovered that a sulphur halide, preferably sulphurmono-chloride (S2C12) properly regulated under suitable reactionconditions, constitutes a highly eflective refining agent and may beemployed as a substitute for the conventional sulphuric acid treatment.

The sulphur halide which I have most successfully employed is themono-chloride (SzClz).

But the di-chloride and tetrachloride of sulphur are ,also useful.Obviously, the same result may be obtained by using other reagents whichreact to form a sulphur halide;

.The principle of'my method consists in treating the impure hydrocarbonswith sulphur chloride so as topi'oduce a reaction between theactualand/or potential gu'm Iorming constitucuts and the sulphurchloride and thus form a gum or tarry fiioduct which is not appreciablyvolatile'at distillation temperatures.

The amount of sulphur chloride nrust be carefully determinedbeI0re.distillation-,'since all ,or I

I the catalyst.

no further amount oi! the reagent should be used must be determined. Y

The exact quantity of the reagent can be determined, for example, byadding small percentages of the same to the oil to be refined, refluxingfor a short time,v and then subjecting the mixture to distillation. Thepurity and other characteristics of the distillate will enable one to.

quickly ascertain the requisite amount of the reagent for the oil. 1

Moreover, all hydrocarbon oils do not show the same velocity of reactionwith the reagent. It is, therefore, necessary to determine the length ofthe treatment with each variety of oil. This reaction velocity isdependent upon temperature, the nature of the oil to be refined, theconcentration and composition of the sulphur chloride, and where acatalyst is employed, the nature of I have found that ordinarily thesulphur chloride should be used in relatively small percentages, usuallyless than 1%. The reaction between the sulphur halide and the oil may,in some cases, be accelerated by a catalyst, such as finely divided clayor fullers earth, copper, lead, zinc and finely divided anhydroussulfides of copper, lead, tin, arsenic and antimony. The-reaction cantake place in the cold, but ordinarily heat will reduce the time period.

The reaction is characterized by (1) chlorination of the valuablealiphatic and aromatic compounds does not take place so that addition orsubstitution chlorinated products of the valuable hydrocarbons are notformed; (2) the potential gum forming constituents of the: oil arereduced or condensed or polymerized to form separable bodies which areinsoluble or are but slightly soluble, i. e., of reduced solubility inthe oil, and

which have a boiling point above that employed for distillation so thatthe valuable constituents of the oil are removable by distillation; (3)formation of substantially ,dry hydrochloric acid gas which, in somecases, may be recovered in the gaseous phase, and (4) the sulphurchloride'reacts upon the potential gum forming constituents and sulphurcompounds of the oil and is in such small percentage that no opportunityis afiorded for the formation either of an increase of sulphurimpurities, or objectionable chlorinated products, both of which wouldimpair the final covery of the valuable and useful hydrocarbons ismaterially increased, as comparedto the sulphuric acid treatment. Theincreased yield is equal to the. amount of the valuable unsaturatedhydrocarbons which are usually destroyed bysulphuric acid treatment, andin'the case of cracked gasolines has amounted to substantially 10%. Thesulphur chloride'is relatively inexpensive and the simplicity of theprocess reduces the refining expense, having in mind particularly thatonly small percentages of sulphur chloride are-employed. The amount ofthe gum or tarry residue obtained is considerably less than the sludgeproduced by the acid treatment.

Further, the handling of large quantities of sulphuric acid with itsattendant problems is avoided.

In addition, there is a substantial reduction in the time period ofoperation.

The gasoline obtained has characteristics which clearly distinguish itfrom the product of the sulphuric acid treatment and has a number ofdefinite advantages.

It is well known, -of course, that aromatic hydrocarbons are desirablein the gasoline; my improved process does not attack the aromatichydrocarbons but preserves the same. The gaso' line produced issubstantially water-white and sweet. Repeated tests have shown that ithas a high octane number as compared to gasoline obtained from the samecrude naphtha by the sulphuric acid treatment. Under comparative testthe product has exhibited an octane number substantially greater thanthe octane number for gasoline produced from the same oil refined by thesulphuric acid treatment. Under the copper-dish test, both the factorsof .corro sion and gum residue are satisfactory. In other words, theproduct is not only satisfactory under the copper-dish test, from thestandpoint of actual and potential gums, but is also comparatively richin the valuable anti-knock constituents which are lost in the sulphuricacid method of refining. An examination of the sulphur content of thegasoline prepared in accordance with this invention discloses that it isless than one-tenth of 1%.

The gasoline is highly stable. Whenallowed to stand for a considerableperiod after distillation, even in the sunlight, it exhibits noappreciable deterioration, whereas gasoline obtained by the. sulphuricacid treatment shows very appreciable deterioration when subjected tothe same tests. More particularly, the product of this process whensubjected to this stability test shows little or no dropping of octanenumber or discoloration, and at the end of the period of test respondsto the copper-dish test equally as well as before exposure.

The process is-applicable to all oils and distillates which normallyrequire chemical refining treatment. I will describe the invention inconnection with the manufacture of gasoline.

Ordinary crude naphthas are treated, such as straight run or crackeddistillates. The oil is tested by refluxing or in any suitable manner todetermine the quantity of potential gum forming constituents and theboiling point. These factors I find determine (1) the quantity orsulphur halide to be added, and (2) the control of the operation.

Where the amount of potential gums is high, a greater percentage of thechemical is employed. In cases where the oil is relatively low boilingor contains appreciable low boiling unsaturated hydrocarbons, thequantity of the chemical is regulated so as 'to avoid chlorination ofthe valuable. low boiling constituents. I have found that the lowboiling hydrocarbons require lesser amounts of the sulphur chloride andthat, in fact, the use of an excessive percentage is objectionable.

- I have found that for most crude naphthas, the percentage ofsulphurhalide need not be in excess .of 1%, the exact percentage beingdetermined as explained by the boiling point and actual and potentialgum content. The amount will vary in the case of raw crudes, or keroseneand lubricating oils.

The oil is treated ina suitable chamber by boiling point, but is speededor accelerated at elevated temperatures. The factors of heat and timerequired to satisfactorily complete the reaction will vary in accordancewith the oil under treatment.

In some cases I find the use of a catalyst oraccelerator, such as one ofthe accelerators above mentioned, will materially decrease the timefactor.

The reaction which takes place, I believe to be 1) a combining of thesulphur chloride with the gum forming and sulphur compound constituentsof the oil with liberation of substantially dry hydrochloric acid gas;(2) the changing or polymerizaticn of these and other deleteriouscompounds into definite relatively stable bodies which are high boiling,separable, i. e., stable abovedistillation, are separable as a residue.

The reaction proceeds with formation of hydrochloric acid gas which isliberated and recovered as a dry gas. The oil under treatment turns adark color and a heavy precipitate forms comprising the gums, resins,and reaction compounds, together with free sulphur. It is noted that theheavy precipitate is much less in quantity than the "sludge or tarformed when a sulphuric acid wash is employed.

, The naphtha so treated is now distilled and this is satisfactorilyaccomplished in any suitable 'fractionating tower s: the usual manner.The

temperatures employed will be determined by the oil under treatment,and, if desired, the distillation may be accomplished under reducedpressure and/or condensing means'disposed in termediate the tower or atthe outlet thereof for returningcertain fractions back to the chamber.

Ilikewise, various of the fractions may be condensed and collected fromthe tower, i. e., separate fractions may be taken off.

The gasoline or distillate upon examination contains a minimum ofdeleterious substances and is much more eflicient from the standpoint ofanti-knock characteristics and more stable than gasolines obtained bychemical treatment with sulphuric acid. In fact, the gasoline recoveredby the present method is remarkably free of gums and resins, as wellassulphur compounds,

. such as mercaptans, polysulphides and other su1-.

phur impurities. The characteristics of the product have been describedabove.

' In practicing the process, any suitable appa ratus may be employed andvarious methods of procedure may be adopted as best suited to plantinstallation. I

In the accompanying drawing,

-reaction processes which have heretofore Figure 1 is a diagrammaticview of a typical apparatus.

Figure 2 is a fragmentary diagrammatic view of a modified form ofapparatus.

Referring to the drawing, I indicates aconventional fractionating columnintowhich the crude naphtha may be-introduced through a pipe ll leadingfrom any suitable source. The lower end of the column forms a residuereceiving chamber l2 having a draw-oil? outlet, and heat may be appliedto the oil within the column as by means of a suitable internal heatingcoil 13. The treating agent, such as sulphur mono-chloride, may beinitially introduced through pipe [9 in a percentage predetermined ashereinbefore described, and the reaction permitted to take placepreferably in the presence of heat supplied by means of the heatingcoil. Such pressures may be employed as will prevent any substantialdistillation of the product during the reaction period. The reactionconditions, however, will be such that hydrochloric acid gas asliberated may be taken ofi through the pipe Id at the upper end of thecolumn and carried either to an absorber and/or to a chamber I 6,wherein chlorine may be separated from the hydrochloric acid gas for thepurpose of supplying additional reagent to the still in furtheroperations. the chlorine liberated in the chamber l6 may be conducted bypipe I! to a chamber l8, wherein it will be comblned'with sulphur in aconventional'manner to produce sulphur chloride. The sulphur chloride.may be conducted as by the pipe IE! to the column, as required. Thesulphur obtained from the reaction in the column may be removed fromtime to time, and treated for use in the chamber l8 to produce thesulphur chloride.

Instead of the apparatus illustrated in Figure 1, it may be desirable,in some instances, to treat the crude naphtha in a chamber independentof the fractionating column and store the same for supply to. thefractionating column as required.

That is to say;

For example, as illustrated in Figure 2, a storage I distillation column2| or a battery of such columns through a pipe or pipes 22.

In order that the practical application of the process may be I moreclearly understood and merely by way of example, I will describe typicalbeen conducted.

Commercial crude naphtha resulting from a cracking process is suppliedto a column, such as illustrated in Figure 1. Into' the naphtha isintroduced 0.6 of 1% of sulphur mono-chloride; the mixture is refluxedfor twenty (20) minutes and heated to the boiling point of thenaphtha.The

oil becomes dark and atarry precipitate and reaction products settleinto the bottom of the chamber. Thereafterthe oil is distilled toapproximately 150 0., or aslong'as the distillate is clear or colorless.It has been observed that at about 1509, it may be desirable .to reducethe pressure in the column, as by evacuation, thereby permitting thedistillation to continue without increasing the temperature to apointwhich will cause the reaction products to vaporize. The dis-- tillationprocess is continued as long as the distillate is clear, It has beenobserved, in some cases,

that it is desirable to keep the distillation temperature below 170 0.,in order to avoid vaporizing or cracking the-reaction products, However,

it will be understood thatthis temperature will vary with differentoils. The distillate produced by this process has been found to. haveall the characteristics hereinbefore described.

As an alternative procedure, the crude naphtha introduced into thechamber maybe partially distilled before introducing the sulphurchloride.

For example, it is distilled sufliciently to take oil the lighterhydrocarbons of low boiling point. In some instances, I have distilledto about 120 C., and the cut taken off up to this temperaturehas beentreated in two ways. For example, (1) it has been given a treatment, of0.1 of 1% of sulphur mono-chloride and because of the character of thedistillate, this can be done at atmospheric temperature and pressure.Ordinarily, it is tilled as long as the distillate has the desiredcharacteristics.

In some instances, it has been found helpful to combine the distillateobtained in the first step with the distillate from the second step, andthen redistill" the mixture to approximately 200 C.

Another method of operation consists in adding theinitial or low boilingdistillate in either treated or untreated condition, as mentioned above,to the remaining undistilled treated bo y of oil, and then distillingthe mixture. In other words, the low boiling constituents and highboiling constituents are each separately chemically treated and thenmixed and distilled. Frequently, it is unnecessary to chemically treatthe low' boiling distillate, and when this is addedtothe body ofundi'stilled treated oil, a small percentage of residual sulphur halidewhich may remain in the treated oil, will be suiilcient to react uponany deleterious substances in the untreated initial distillate. @Suchmixture of untreated low boiling distillate and treated oil will bedistilled, as described;

I further proceed by reacting upon the oil to be treated with a verysmall percentage of the sulphur halide, and distilling ofl fractions ofthe oil as long as their recovery indicates they are the valuable onesor the ones desired, and are free of deleterious substances. Whenthisceases, the fractionation is discontinued, and another compounds ofreduced solubility, and separating small percentage of sulphur halide isadded and allowed to react with the remaining body of oil. When thereaction has been completed, distillation and fractionation are resumed.This semicontinuous and partial treatment with relatively smallpercentages of sulphur halide, followed by distillation, may be carriedon until .no more desirable fractions are recovered and assures that arelatively high yield, 1. e., substantially all of the valuableconstituents, will be obtained.

. As explained, it maybe desirable ,to employ a catalyst, such as one ofthose described above preferably in finely divided condition, and thesehave been used with satisfactory results in each of the processesdescribed. Y

With reference to the treatment of raw crudes, oils derived from thetreatment of shales, and liquid coke-oven products, 1. e., light oilsand distillates thereof, it will be understoodthat the sulphur chloridewill be added in amounts and con- 'light oils and distillates thereof,in liquid phase to obtain products free of potential gum-formingsubstances and undesirable sulphur compounds, which comprises reactingupon the oil containing the said substances with up.to one percent ofsulphur chloride, thereby polymerizing the said substances intorelatively high boiling and stable out such high boiling coinpounds.-

2. The process of chemically treating petroleum hydrocarbon oils anddistillates thereof and light-oils and distillates thereof, in liquidphase,

substances and undesirable sulphur compounds,

which comprises reactingupon the oil containing the said substances withup to one percent of sulphur mono-chloride, thereby polymerizing thesaid substances into relatively high boiling and stable compounds ofreduced solubility, and separating out said'high boiling compounds.

3. A process in accordance with claim 1 in which the reaction of the oilwith sulphur chloride takes place in the presence. of a catalyst.

WALTER A. PATRICK, JR.

